A number of benefits can be obtained by manufacturing certain functional components within a vacuum environment. In view of these advantages, vacuum processing systems for the processing of various substrates have been developed. Typically, a vacuum processing system has a centralized transfer chamber mounted on a monolith platform. The transfer chamber is the center of activity for the movement of the substrate being processed in the system. Substrates are generally in the transfer chamber only long enough to be transferred to another chamber for storing or processing. One or more process chambers attach to the transfer chamber at valves through which substrates are passed by a robot in the transfer chamber. The valves close in order to isolate the process chambers while substrates are being processed therein.
Physically, the process chambers are either supported by the transfer chamber and its platform or are supported on their own platform. Inside the system, the transfer chamber is typically held at a constant vacuum, whereas, the process chambers may be pumped to a greater vacuum for performing their respective processes. Following processing, the pressure of the process chamber must be returned to the level in the transfer chamber before opening the valve to permit access between the chambers.
Access to the transfer chamber for substrates from the exterior of the system, or from the manufacturing facility, is typically through one or more load lock chambers. The load lock chambers cycle between the pressure level of the ambient environment and the pressure level in the transfer chamber in order for the substrates to be passed, so the load lock chambers transition the substrates between the atmospheric pressure of a very clean environment to the vacuum of the transfer chamber.
Some common transfer chambers have facets for four to six process chambers and load lock chambers. For a six-faceted transfer chamber, typically two of the facets are for load lock chambers, and the other four facets are for process chambers. The process chambers include rapid thermal processing (RTP) chambers, physical vapor deposition (PVD) chambers, chemical vapor deposition (CVD) chambers, etch chambers, etc. The productivity of a vacuum processing system is increased when more process chambers are mounted to the transfer chamber, because more substrates can be processed at a given time. Additionally, less space is required in the manufacturing facility if the productivity of the system is maximized. Thus, there is a need for larger transfer chamber to allow the mounting of a greater number of process chambers.
In addition, certain substrates to be processed are very large, and thus require a large transfer chamber to allow processing of the substrate. For example, glass plates of certain flat-panel plasma displays are processed using thin-film techniques to deposit horizontal electrodes and vertical column electrodes onto the glass. Since it is desirable to process very large plates of glass for this purpose, a very large transfer chamber is necessary to manipulate the glass substrate for transfer to a processing unit.
It is desirable to keep the volume of the larger transfer chamber to a minimum in order to decrease manufacturing costs, increase efficiency of the chamber, and to reduce the effects of contamination due to microparticulate matter within the chamber. There is thus a need in the art for a vacuum processing system with improved capacity and efficiency for high throughput production of processed substrates.